Solvent-Free Covalent Functionalization of Fullerene C60 and Pristine Multi-Walled Carbon Nanotubes with Crown Ethers.

The goal of the present work was to test the feasibility of simple, one-step and solvent-free covalent functionalization of pristine multi-walled carbon nanotubes (MWNTs) and fullerene C60 (as a model system) with amino-substituted crown ethers, namely, 4'-aminobenzo-15-crown-5 and 4'-aminobenzo-1 8-crown-6. The attachment technique proposed is based on thermal instead of chemical activation, and can be considered as ecologically friendly. The suggested covalent binding mechanism is the nucleophilic addition of amino functionalities of crown ethers to the 6,6 bonds of pyracylene units in the case of C60, and to pentagonal (and probably other) defects of similar nature in the case of pristine MWNTs.

Interaction of a Ni(II) tetraazaannulene complex with elongated fullerenes as simple models for carbon nanotubes.

Nickel(II) complex of 5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecine (NiTMTAA), which can be employed for noncovalent functionalization of carbon nanotubes (CNTs), represents a more complex and interesting case in terms of structure of the resulting nanohybrids, as compared to the related materials functionalized with porphyrins and phthalocyanines. Due to its saddle shape, the NiTMTAA molecule adsorbed can adopt different, energetically non-equivalent orientations with respect to CNT, depending on whether CH3 or C6H4 groups contact the latter. The main goal of the present work was to provide information on the interactions of NiTMTAA with simple single-walled CNT (SWNT) models accessible for dispersion-corrected DFT calculations.

Noncovalent functionalization of graphene with a Ni(II) tetraaza[14]annulene complex.

The few-layer graphene, produced by exfoliation of graphite in 4-methylanisole, was noncovalently functionalized with the Ni(ii) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12,14-hexaene (Ni(ii)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA), which is a simple model of more complex porphyrins and phthalocyanines. The resulting hybrid materials with different content of NiTMTAA were characterized by means of thermogravimetric analysis, scanning and transmission electron microscopy (SEM and TEM, respectively), atomic force microscopy (AFM), energy dispersive X-ray, Fourier-transform infrared (FTIR), Raman and UV-visible spectroscopy, as well as fluorescence and conductivity measurements. Additional information on the mechanisms of NiTMTAA interaction with graphene was obtained from density functional theory (DFT) and molecular mechanics (MM) calculations.